Lubricants containing zinc dithiophosphates



3,290,246 LUBRICANTS CONTAINING ZINC DITHIOPHOSPHATES Emilio Perrotti, San Donato Milanese, and Sergio Del Ross, Milan, Italy, assignors to SNAM S.p.A., Milan,

Italy, a company of Italy No Drawing. Filed Sept. 4, 1963, Ser. No. 306,630

Claims priority, application Italy, Sept. 7, 1962,

Patent 692,797 10 Claims. (Cl. 25232.7)

This invention relates to a lubricant composition having improved antioxidant, antiwear and antirust properties.

It is known that zinc dialkyl-dithiophosphates are used as additives for lubricant oils, since these compounds have, in addition to a marked antioxidant activity, some antiweaffeatures and good anticorrosion properties.

Itis also known that amine compounds are commonly employed as antioxidant additives, but they often have the disadvantage of imparting brown coloration and of causing deposits in lubricant oils which are thus degraded.

We have now found and prepared compounds having high antioxidant activity, and having the general formula: RO\fi on (1 PS-Zn-SP R'o OR wherein the RO group is an alcohol radical capable of making the final product soluble in mineral oils and R is an amino alcohol radical, an amino phenol radical or a heterocyclic nitrogen-containing alcohol radical.

Thus according to this invention there is provided a lubricant composition comprising a mineral oil and a compound having the general Formula 1 above.

The compound of Formula I is preferably present in an amount up to 1.5% by weight.

Since the radicals OR and OR are responsible for the antioxidant activity of the final product, we have pre- CHZY X err-on (any CH2O"H ino-H (II) (III) respectively, wherein X represents a hydrogen atom or a hydrocarbon radical, e.g. CH and Y represents a nitrogen-containing radical in which the nitrogen is present as amine nitrogen or as a heteroatom, e.g.

As examples of amino alcohols may be mentioned the following compounds derived from Formulae II and III:

C6115 Cn 5 OHz-N ITIH I N'OH3 (EH1 CHCH ([3112 C HGH; (IIHOH (IJHOH CHZOH CH CH azsazis Patented Dec. 6, 1966 NH N-OHa IITH IIYH l CHCH; ([JHCH; (EH2 CHCH; CHOH CHOH CHOH CHOH CH3 CH3 CH CH We have also carried out some investigations with compounds wherein R0 represents:

in order to provide a comparison with commercial alkyldithiophosphates.

We have discovered that the more active zinc alkyldithiophosphates are those derived from secondary alcohols,

whilst those derived from primary and tertiary alcohols show substantially no activity.

Examples of amino phenols are:

4-dodecyl-2-piperidinomethylphenol and 4-tert.butyl-2-piperidinomethylphenol In order to best illustrate the invention, we shall now describe the preparation of preferred alcohol used in the production of the compounds used in the composition of this invention, and also the preparation of such compounds.

(A) PREPARATION OF AMINO PHENOLS AND AMINO ALCOHOLS 4 dodecyl-2-piperidin0methylphen0l.The p.dodecylphenol is obtained with quantitative yields by alky'lating phenol with commercial tetrapropylene; it is a viscous yellow liquid having a B.P. of 150 C. under 0.3 mm. Hg. From this, by treatment with piperidine and formaldehyde, the 4-dodecyl-2-piperidinomethylphenol is obtained, which is a viscous liquid boiling at 170 l90 under 0.2 mm. Hg. The yieldis Analysis.Calculated for C H NO: C=80.18%, H =11.50%, N=3.89%. Found: C=80.74%, H=1l.l6%, N=3.90%.

3-methyl-butanol.This compound was prepared by treating methylmagnesium iodide in anhydrous ether with isobutyraldehyde, according to the known art. Colourless liquid having B.P. 1l0111 C.

4-methyl-2-pentan0l.As in the above lower homolo gous compound, this was obtained by treating acetaldehyde in anhydrous ether with isobutylmagnesium bromide. Colourless liquid having B.P. 133 C.

Z-methyl-3-anilinopropano-L-This compound was obtained by reacting aniline with methallyl alcohol in the presence of powdered sodium hydroxide using the known process employed for producing allyl alcohol. 0.2 mol of alcohol and 0.1 mol of aniline are heated at boiling temperature for 24 hours in the presence of 0.1 g. of fused and powdered sodium hydroxide. A yellow liquid having B.P. 99100 C. under 0.1 mm. Hg.

Analysis.Calcu lated for C H NO: C=72.69%, H =9.l5%, N=8.48%. Found: C=72.46%, H=8.83%,

The conversion of the final product is in the order of 20%. By operating under pressure at a higher temperature, it is possible to obtain the amino alcohol with greater conversions and yields.

3-cyclohexylamina-Z-bntanol.This compound was obtained by reacting cyclohexylamine with 3-chloro-2- butanol in the following way: 5.4 g. 3-chloro-2-butanol and 10 g. cyclohexylamine are mixed; this mixture, which J-(N-methylanilino)-ispropanol.-This compound was is exothermic, is kept at the room temperature for 30 minobtained by reacting methylaniline with propylene oxide utes and thereafter is kept at 100 C. for 1 hour. White in the following Way: 11 g. propylene oxide, 22 g. methylcrystals of the hydrochlorate are separated. The reaction aniline and 0.05 g. KOH in 20 cc. methyl alcohol are mass is made alkaline and the compound is extracted and mildly boiled for 2 hours; thereafter, to this solution then distilled under reduced pressure. 5.7 g. of a prodcc. water are added and the boiling is continued for a 10 Hot boiling at 122-125 C. under 10 mm. Hg. are obfurther 2 hours. This solution is poured in abundant tained. The product is an oily, colourless liquid. water, and the product is extracted. By fractional distilla- Analysis. Calculated for C H NO: C=70.l0%, tion 15.5 g. of the compound are obtained. A viscous, H=12.36%, N=8.17%. Found: C=69.90%, H= yellow oil having a pleasant smell and B.P. l10111 C. 11.98%, N=7.80%. under 2 (B) PREPARATION OF ZINC AMINO-ARYL- Analysis.-Calculated for C H NO: C=72.68%, H =9.15%. N=8.48%. Found: c=72.53%, H=9.03%, AND AMINOALKYL DITHIOPHOSPHATES These compounds, which will individually be described 3-(N-methylanilin0)-2-buian0l.-This compound was hereinafter, are very viscous liquids, insoluble in water prepared in a manner similar to the preceding compound, and Soluble in -P Organic s01Vfmts- This enables by reacting methylaniline with 2,3-epoxy-butane. 18 g. y Purification from mineral impurities- 2,3-epoxy-butane, 27 g. methylaniline and 30 cc. methyl Th$e Compounds are P p y reading alcohols or alcohol are boiled for 24 hours. The solution is poured Ph with Phosphorus Pentasulphide ill the molar ratio into water, and the extracted oil is fractionally distilled. :1, a cordi to the following equation:

10 g. of an oily, yellow product, boiling at 95 C. under 4ROH+P2S5=2(RO)2PSSH+H S 0.2 mm. Hg are obtained. 2

Analysis. Calculated for CHHHNO: C:73 7O%, wherein R is an alkyl or aryl group. The alkylor aryl- H=9 46%, Found: C=73 25%, dlthiophosphonic acids so obtained are neutralized using sodium hydroxide; from the sodium salts zinc salts are 3-anilino-2-butanol. This compound was prepared obtamcd by interaction in a manner similar to the preceding compound, b r -2 mol of cetyl alcohol and 0.2 mol of the ROH comacting aniline with z,3 epoxy butane 18 aniline, 72 pound under test, dissolved in 100 cc. anhydrous benzene g. butylene oxide and 0.2 g. potassium hydroxide in 20 are added to a suspenslon of mol 2 5 using cc. methyl alcohol are boiled for 24 hours. This solution 9 anhydrous benzelm The mixture is 146131 is poured into Water and the extracted oil is fractionally p f g the solid disappear 51 a Portion of the Solvent distillei 12 of an oily yellow compound, boiling at 1s dlstllled ol'f, and the filtered solution is neutralized, 0 under 02 mm Hg are collected. under stirring, using 10% sodium hydroxide solution in Analysis Calculated for CmHlsNO; 027270170 the presence of phenolphthalein. To the suspension of H=9 16%, Found: C=72 35% sodium salt the equivalent of zinc chloride solution is g 40 added, under vigorous stirring, adding, if necessary, fur- Lanilino is0pmpan0l. ThiS compound was prepared ther solvent, and finally the organic phase is separated, in a manner similar to the preceding compounds, by reand Concfintrated undfir reduced Pressureacting aniline with propylene oxide, under pressure, at 1 W144 P p y a temperature from 115 to 130 C, dlthzophosphate. -V1scous oil, slightly soluble in gaso- The results of the tests are tabulated in the Table L line, very soluble in benzene, slightly soluble in mineral from which it is seen that the best operative conditions 0115- correspond to those of test 6. The reaction by-product Analysls- Calculated for 64 114 2 4 4 z is probably a compound of the formula: C=62-44%: Found! C=62.61%, H=9.53%, N=2.41%, S=11.l3%. UHr-CHOH-CHK Zinccetyl -(4 dodecyl 2 piperidinomethylphenyl) COHEN dithiophosphate.-Viscous, grey liquid, very soluble in CHPCHOEPOHZ non-polar solvents, slightly soluble in ethyl alcohol.

Analysis. Calculated for C H N O S P Zn: which result-s from the reaction of l-anilino isopropanol C=66.2%, H=10.67%, N=l.93%, S=4.41%. Found: with propylene oxide. 55 C=65.81%, H: 10.12%, N=2.32%, S=4.91%.

The l-anilino isopropanol is a viscous, yellow oil hav- Zinc cetyl-(isobntyl)-dithi0pl10sphate. Waxy, yellow ing aromatic smell, very soluble in organic solvents, boilsolid melting at 4244 C., very soluble in all the noning at C. under 0.2 mm. Hg. polar solvents and in mineral oils.

Analysis. Calculated for C H NO: C'=71.50%, Analysis. Calculated for C H O S P Zn: C: H=8.68%, N=9.27%. Found: C=7l.93%, H=8.9l%, 60 54.30%, =9.57%, S=14.50%- Found: C=54.90%, N=9.40%. H=10.00%, S=13.98%.

Table I Numbertest wi liife pi g 'jl r ie "iffailiiliiig Catalyst giiid iie if T ziiigij il ii r iit a Reslgduali oxide (mols) percent t- 3 i 1311 3: 395 2 1 1.01 N.D. 3.5 2 1 1. 03 N.D. 3.5 3 1 2- 04 ND. 1.6 3 1 2.03 5 1.7 2 1 1. 05 s 3.4 1 1 0-2 17 4.6

Zinc (2 -methyl-.i-anilinopropyl)-dithiph0sphate. Viscous, orange oil, very soluble in the non-polar solvents and in oils.

Analysis. Calculated for C H O N S P Zn: O: 58.53%, H=8.90%, N=2.63%, S= l2.05%. Found: C==60.07%, H=9.37%, N=2.66%, S=1l.78%.

Zinc cetyl-(Z-butyl)-dithi0ph0sphate.Waxy, white, or slightly yellow, solid melting at 4045 C., very soluble in non-polar organic solvents. Soluble in mineral oils..

Analysis.Calcd. for C4QH8QO4S4P2ZHI H=9.72%, S=l-4.05%. Found: C=55.10%, H: 10.00%, S=13.57%.

Zinc cetyl (4 methyl 2 pentyl)-dithi0ph0sphate.- Waxy, white, or slightly yellow coloured, solid melting at 3642 0., very soluble in organic solvents and mineral oils.

Analysis.Calcd. for C44H9204S4P2Z1'1I S=13.64%. Found: C=56.35%, H: 9.70%, S=13.30%.

Zinc bis-(4-methyl-2-pentyl)-dithi0phosphate. Waxy solid very soluble in non-polar organic solvents and very soluble in mineral oils. It was prepared by reacting 4- methyl-Z-pentanol with phosphorus pentasulphide, in the molar ratio 4:1.

Zinc cetyl (4 piperidine 3-methyl-2-butyl)-dithi0- phosphate.Viscous and turbid liquid, fairly soluble in organic solvents and slightly soluble in mineral oils. I Analysis.Calcd. for C5 H1o N2O4S4P2Zni H=9.90%, N=2.60%, S=11.88%. Found: C: 58.40%, H=10.12%, N=2.35%, 'S=11.12%.

Zinc cetyl [3 (N methylanilino)-2-pr0pyl]-dithioph0sphate.-Viscous, yellow, slightly turbid liquid, soluble in non-polar organic solvents and fairly soluble in mineral oils.

Analysis.Calcd. for C H N O S P Zn: C=53.53%, H=8.90%, N=2.63%, S:12.05%. Found: C: 58.40%, H=9.0'2%, N:2.87%, S=12.83%.

Zinc cetyl (3-anilin0-2-bu'tyl)-dithi0phosphate. Viscous, yellow, slightly turbid liquid very soluble in nonpolar organic solvents, and fairly soluble in mineral oils.

' the employed sodium hydroxide.

theoretical (665 cc.). The sodium salt separates as a gelatinous mass.

The zinc salt is prepared by adding, under vigorous stirring, a 2 N solution of zinc chloride in a 10% excess over The solution is stirred for 15 minutes, and then the organic phase separates, which, after drying on sodium sulphate, is rapidly concentrated under reduced pressure, to avoid prolonged heating.

The dithiophosphate (329 g.: yield 94 to 95%) is a viscous, greenish yellow oil. It is very soluble in benzene and gasoline, and sufficiently soluble in mineral oils also if they have a high degree of viscosity.

Analysis.Calcd. for C H N O S P Zn: C='57.80%, H=8.73 N=2.69%, S=12.34%, Zn=6.30%. Found: C=58.16%, H=9.04%, N=2.88%, S=12.54%, Zn: 6.00%.

Zinc cetyl (3 cyclohexylamino 2 butyl)-dithi0ph0sphate.-Viscous oil, soluble in non-polar solvents, not very soluble in mineral oils.

Analysis.Calcd. for C H N O S P Zn: C=57.88%, H=9.90%, N=2.60%, S=1l.88%. Found: C: 58.50%, H=10.11%, N=2.40%, S=11.83%.

(C) BEHAVIOUR OF ADDITIVES UNDER OXIDA- TION, ANTIWEAR AND ANTIRUST TESTS.

(a) Oxidations tests.In Table II there are tabulated the results obtained from a series of tests which indicate the anti-oxidising properties of the products prepared according to this invention. The oxidation test was carried out according to the prescription of ASTM/D943 (NOM/ M62); the Staeger test was carried out according to the standards of Cornitat-o Elettrotecnico Italiano, consisting of heating the oil at 110 C. in the presence of a copper catalyst. When the test is completed, the alterations in the neturalisation number and the amount of eventually formed deposit are recorded; alternatively, the number of hours required to attain an increase of 0.25 in the neutralisation number is recorded. The compounds listed in the table were tested in oil formulations containing 0.06% of the compound under test, in the presence of 0.2% of a phenol (2,6-tert.butyl-p-cresol), 1.5% of a H=8.90% N=2.63 S= 12.05%. Found: C: commercial rust-proofing product and 0.005% of a com- 59.01%, H=9.05%, N=2.48%, S=11.70%. mercial demulslfylng agent.

Table II Naturali- Time of Time of sation Demul- .ASTM- oxidation Compound under test number sivity D-943 1 Staeger KOH, in secs. NOM/M62 test (hrs) mg./g. test (hrs) Zinc cetyl-lsobutyl-dithiophosphate 0.21 290 '840 Zinc cetyl-(3 amilino-2-methyl-l-propy1)- dithiophosphate- 0. 15 250 1, 848 432 Zinc cetyl-(Z-butyl)-dithiophosphate- 1,176 Zinc bis-( i-rnethyl-2-pentyl)-dithioph phate 0. 19 244 1, 344 792 Zinc cetyl-( l-piperidino-3-methyl-2-butylydithiophosphate 0. 16 303 1, 680 576 Zinc cetyl-[3-(N-methylanilino)-2propyl] dithiophosphate 0. 21 237 2, 184 576 Zinc cetyl-(3-anllino-2-butyl)-1iithiophosphate 0. 21 220 3, 024 576 Zinc cetyl-(3-anilino-2-pr0pyl)-dithiophos- V phate 0. 21 215 3, 300, 864 Zinc cetyl-(3-cyclohexylamino-Z-butyl)- dithiophosphate 0. 13 237 2, 352 503 Zinc cetyl-(3-anilino-2-propyl)dithi0ph0sphate. This product was prepared in the following way: In a 2 litre flask, 74 g. of depurated P 8 and 350 cc. of dry benzene are introduced; this mixture is heated to boiling, and a solution of 161.3 g. cetyl alcohol and 101 g. 3-aniline-2- propanol in 300 cc. of dry benzene is added for 10 minutes. This mixture is kept boiling for 30 minutes, and during this time the pentasulphite is almost totally reacted. The hydrogen sulphite is removed by partial vaporisation under reduced pressure. The filtered solution is diluted with benzene (2 litres) and neutralised with 1 N aqueous sodium hydroxide. Under vigorous stirring, 590 cc. of

From the results tabulated in Table II it is clear that the presence of both a secondary alcohol group and an amino group in the molecule, designated as R0 in the general Formula I, give the compounds used in the present invention as astonishing activity, and that, amongst the amino groups, the arylamino groups are the most active.

Finally, remarkable results can be obtained when the amino alcohol used in the preparation of the compound has both a secondary alcohol group and a secondary aromatic amine group. In fact, both zinc cetyl-(3-analino-2- butyl)-dithiophosphate and zinc ccty1-(3-anilino-2- propyl)-dithiophosphatc, and particularly the latter, have the solution are obtained, corresponding to 88% of the an activity which is about three times that shown by zinc A zinc cetyl-(3-ani1in0-2-propy1)-dithi0phosphate.

ferent commercial compounds, all based on dithiophospha as additives.

where R'O is a secondary alcohol radical, and R is selected from the group consisting of amino phenols having the structural formula HO- R Z, where R; is selected from the group consisting of phenylene and alkylphenylene, and Z is piperidinomethyl, and of primary and secondary alcohols having the formulae:

l l GEE-CH3 and OHY CHzO-H (JED-H where X is selected from the group consisting of hydrogen and lower alkyls and Y is a nitrogen-containing radical in which the nitrogen is present as amine nitrogen or as a heteroatom, and is selected from the group c0nsisting of N: --CHz, l r-on @t 3? 2. A composition according to claim 1, in which the R0 radical is selected from the group consisting of CHZY X (DH-CH and ()HY CHzO- CH0- wherein X represents a hydrogen atom or hydrocarbon radical selected from the group consisting of methyl, ethyl, propyl and Y is a nitrogen containing radical selected from the group consisting of 3. A composition according to claim 1 in which the R'O radical has the formula C H O--, and n is between 4 and 20.

4. A composition according to claim 3 in which the RO radical has the formula C H O-.

5. A composition according to claim 1 in which the R radical is 3-anilino-2-propyl.

6. A composition according to claim 5 in which the compound of Formula I is zinc cetyl-(3-anilino-2-propyl)- dithiophosphate.

7. A composition according to claim 1 in which the compound of Formula I is zinc cetyl-(3-anilino-2-butyl)- dithiophosphate.

8. A composition according to claim 1, in which the compound of Formula I is present in an amount up to 1.5%.

9. A composition according to claim 1 in which the RO radical is selected from the group consisting of 4-dodecy1- 2 piperidinomethyl phenoxy, 2 methyl-3-anilino-1-propoxy, 1 (N methyl anilino) isopropoxy, 3 (N-methyl anilino) 2 butoxy, 3-anilino-2-butoxy, l-anilino isopropoxy, and 3-cyclohexylamino-Z-butoxy.

10. A composition according to claim 1 in which the compound of Formula I is selected from the group consisting of zinc cetyl (4 -tert.buty1- 2 piperidine-methylpheny1)-dithiophosphate, zinc cetyl-(4-dodecyl-2-piperidine-methylphenyl)dithiophosphate, zinc cetyl-(3-aniline- 2-methyl-1-propy1)-dithiophosphate, zinc cetyl-(4-piperidine 3 methyl 2-butyl)-dithiophosphate, zinc cetyl-(N- methyl-3-aniline-2-propyl)-dithiophosphate, zinc cetyl-(3- aniline-Z-butyl)-dithiophosphate, zinc cetyl-(3-aniline-2- propyl)-dithiophosphate, and zinc cetyl-(3-cyclohexy1- amino-Z-butyl) -dithiophosphate.

References Cited by the Examiner UNITED STATES PATENTS 2,973,323 2/1961 Millikan et al 25232.7 2,977,382 3/1961 Millikan 25232.7 X 3,002,014 9/1961 Dinsmore et al. 252---32.7 X

DANIEL E. WYMAN, Primary Examiner.

P. P. GARVIN, Assistant Examiner. 

1. A LUBRICANT COMPOSITION COMPRISING A MAJOR AMOUNT OF A MINERAL OIL AND A MINOR AMOUNT, SUFFICIENT TO IMPROVE THE ANTIOXIDANT, ANTIWEAR AND ANTIRUST PROPERTIES OF THE OIL, OF A COMPOUND HAVING THE GENERAL FORMULA: 